TWI659003B - Ion exchangeable glass article for three-dimensional forming - Google Patents

Abstract

An alkaline aluminosilicate glass that can be chemically strengthened and shaped into a three-dimensional shape. Glass has a softening point of less than about 825 ° C and a high-temperature thermal expansion coefficient of less than about 30 parts per million (ppm) / ° C. After forming the three-dimensional shape, the glass can be subjected to ion exchange. When ion exchanged, glass has a surface layer that is under a compressive stress of at least about 700 MPa.

Description

Ion-exchangeable glass object for three-dimensional forming [Related applications]

This application claims priority right of U.S. Provisional Application No. 61/945430, filed on February 27, 2014 in accordance with the Patent Law. This case is based on the contents of the provisional application and the provisional application is fully incorporated by reference Into this article.

The present disclosure relates to a glass that can be formed into a three-dimensional shape. More specifically, the present disclosure relates to an ion exchange glass that can be formed into a three-dimensional shape. Even more specifically, this disclosure relates to such glasses with low softening points.

Shaped glass objects are beginning to be used as exterior shields or housing elements in consumer electronics devices such as mobile phones and tablets. Currently, such objects are produced by molding glass.

This disclosure addresses these and other needs by providing a basic aluminosilicate glass that can be chemically strengthened and shaped into three Dimensional shape. The glass has a softening point of less than about 825 ° C and a high-temperature thermal expansion coefficient of less than about 30 parts per million (ppm) / ° C. After forming the three-dimensional shape, the glass can be subjected to ion exchange. When ion exchanged, glass has a surface layer that is under a compressive stress of at least about 700 MPa.

Accordingly, one aspect of the present disclosure to provide a glass-like article, the glass article comprises at least about 50 mole% of SiO _2, at least about 8 mole% of Al ₂ O _3, at least about 1 mole% P ₂ O ₅ and at least about 12 mole% Na ₂ O. Glass articles are ion-exchangeable and have a softening point of less than or equal to about 825 ° C and a high-temperature thermal expansion coefficient of less than or equal to 30 ppm / ° C.

The second aspect of the present disclosure will provide a kind of glass objects, the glass article comprises at least about 50 mole% of SiO _2, at least about 8 mole% of Al ₂ O _3, at least about 1 mole% of P ₂ O ₅ and at least about 12 mole% Na ₂ O. The glass object is an ion exchange type and has a compression layer having a layer depth extending from the surface of the glass object into the object, wherein the compression layer has a maximum compression stress of at least about 700 MPa. The glass article has a softening point of less than or equal to about 825 ° C and a high-temperature thermal expansion coefficient of less than or equal to 29 ppm / ° C.

These and other aspects, advantages, and distinguishing features will become apparent from the following detailed description, the accompanying drawings, and the scope of the accompanying patent applications.

200‧‧‧ dish

202‧‧‧Main surface

204‧‧‧ main surface

210‧‧‧ generally flat or flat

220‧‧‧ curved part

230‧‧‧Dishes

232‧‧‧Main surface

234‧‧‧Main surface

300‧‧‧ glass objects

310‧‧‧first surface

312‧‧‧Second Surface

320‧‧‧first compression layer

322‧‧‧second compression layer

330‧‧‧Central area

Figure 1 is a graph of the instantaneous thermal expansion coefficient of sample 20 in Table 1 as a function of temperature; Figure 2 is a schematic cross-sectional view of a dish-shaped glass object; and Figure 3 is a schematic cross-sectional view of a flat ion-exchange glass object.

In the following description, through the several views shown in the drawings, the same element symbol indicates the same or corresponding element. It should also be understood that, unless otherwise specified, terms such as "top", "bottom", "outward", "inward" are convenient terms and are not intended to be considered limiting terms. In addition, it should be understood that whenever a group is described as including at least one of a group of elements and combinations of elements, the group may include any number of the described elements, and substantially any number of them. The elements are composed, or consist of any number of them, which are described individually or in combination with each other. Similarly, it should be understood that whenever a group is described as comprising at least one of a group of elements and combinations of elements, the group may be composed of any number of the elements individually or in combination with each other. Unless stated otherwise, when stated, a value range includes the upper and lower limits of the range and any range therebetween. Unless otherwise specified, the indefinite articles "a", "an" and the corresponding definite article "the" as used herein mean "at least one" or "one or more". It should also be understood that the various features disclosed in this description and the drawings may be used in any and all combinations.

As used herein, the terms "glass article" and "multiple glass articles" are used in the broadest sense to include any article made entirely or partially of glass. Unless otherwise specified, all mole fractions are expressed as mole percentages (mol%). The high-temperature thermal expansion coefficient (high-temperature CTE) is expressed in parts per million (ppm) / degrees Celsius (ppm / ° C), and the high-temperature thermal expansion coefficient represents a value measured in a high-temperature flat line region of an instantaneous CTE versus temperature curve.

Unless otherwise specified, all temperatures are expressed in degrees Celsius (° C). As used herein, the term "softening point" refers to the temperature at which the viscosity of the glass is at about 10 ^7.6 poise (P), the term "annealing point" refers to the temperature at which the viscosity of the glass is at about 10 ^13.2 poise, and the term "200 poise temperature (T ^“200P ” ”refers to a temperature at which the viscosity of the glass is at about 200 poise, and the term“ 1 poise temperature (T ^200P ) ”refers to a temperature at which the viscosity of the glass is at about 200 poise, and the term“ 10 ¹¹ poise temperature ”means that the viscosity of the glass is 10 The temperature at ¹¹ poise, the term "35kP temperature (T ^35kP )" refers to the temperature at which the glass viscosity is about 35 ^kilopoise (kP), and the term "160kP temperature (T ^160kP )" refers to the glass viscosity at about 160kP temperature.

As used herein, the term "zircon decomposition temperature" or "T ^{decomposition} " refers to the temperature at which zircon-commonly used in refractory materials in glass processing and manufacturing-decomposes to form zirconia and silicon dioxide, and the term ""Zircon decomposition viscosity" refers to the viscosity of glass under T ^{decomposition} . The term "liquid phase viscosity" refers to the viscosity of the molten glass at the liquid phase temperature, where the liquid phase temperature refers to the temperature when the crystals that first appear as molten glass cool down from the melting temperature, or finally when the temperature rises from room temperature The temperature at which the crystals melt.

It should be noted that the terms "substantially" and "about" may be used herein to indicate an inherent degree of uncertainty that can be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also used herein to indicate that the quantitative representation can vary from the cited reference to a degree that does not cause a change in the basic functional aspects of the subject in question. Thus, for example, a "substantially lithium-free" glass is a glass in which lithium and lithium-containing compounds are not actively added or batched into the glass, but can be present as very small amounts of contaminants.

The Vickers crack initiation threshold described herein is determined by applying an indentation load to the glass surface at a rate of 0.2 mm / minute and subsequent removal. Hold the maximum indentation load for 10 seconds. Define the indentation crack threshold under the indentation load. 50% of the 10 indentations under indentation load showed any number of radial / intermediate cracks originating from the indentation pressing angle. Increase the maximum load until the threshold for a given glass composition is reached. All indentation measurements were performed at room temperature of 50% relative humidity.

As used herein, "maximum compressive stress" refers to the highest compressive stress value measured in the compression layer. In some embodiments, the maximum compressive stress is located on the glass surface and may appear as a "spike" in the compressive stress profile. In other embodiments, the maximum compressive stress may occur at a depth below the surface, providing a compressive profile with the appearance of a "buried peak". Compressive stress and layer depth are measured using other means known in the art. Such means include, but are not limited to, measurement of surface stress (FSM) using commercially available instruments such as FSM-6000 manufactured by Luceo Co., Ltd. (Tokyo, Japan), and the like; and In ASTM 1422C-99 titled "Standard Specification for Chemically Strengthened Flat Glass" and titled "Standard Test Method for Non-Destructive Photoelastic Measurement of Edge and Surface Stresses in Annealed, Heat-Strengthened, and Fully-Tempered Flat Glass" Methods for measuring compressive stress and layer depth are described in ASTM 1279.19779, the contents of which are incorporated herein by reference in their entirety. Surface stress measurement relies on the accurate measurement of stress optical coefficient (SOC), which is related to the birefringence of glass and is expressed in nm / mm / MPa. The SOC is then measured by other methods known in the art, such as the fiber and four-point bending methods, both of which are in ASTM Standard C770- entitled "Standard Test Method for Measurement of Glass Stress-Optical Coefficient" 98 (2008) describes the content of these documents by reference Incorporated herein, as well as the bulk cylinder method.

The term "three-dimensional shape" as used herein refers to a shape or form other than a flat sheet. The three-dimensional shape is not in a plane. Figure 2 illustrates a non-limiting example of a three-dimensional glass object. The dish 200 has two major surfaces 202, 204, each major surface having a generally flat or planar portion 210 surrounded by a curved portion 220 on either end (or alternatively on both ends) Bundles to provide a dish-like outline or appearance. In other embodiments, the dish 230 has only one major surface 234 having a substantially flat or planar portion 210 that is bent on either end (or alternatively on both ends). Section 220 surrounds the bundle. The remaining major surface 232 is substantially flat or planar.

Referring generally to the drawings and particularly to Figure 1, it should be understood that these drawings are for the purpose of describing particular embodiments and are not intended to limit the scope of this disclosure or the accompanying patent applications. The drawings are not necessarily drawn to scale, and for clarity and conciseness, certain features and certain views in the drawings may be exaggerated to scale or schematic.

In order for the glass to be formed into a three-dimensional shape for use as a cover glass in a handheld electronic device, the glass should have a low softening point to facilitate forming and a coefficient of thermal expansion (CTE) sufficiently low at high temperatures to prevent cracking. In addition, the glass should be ion-exchangeable to achieve a surface compressive stress sufficient to prevent damage from impact.

Described herein is a series of glasses that are melt-formable, ion-exchangeable, and formable into three-dimensional shapes. Glass comprises at least about 50 mole% of SiO _2; at least about 8 mole% of Al ₂ O _3; at least about 1 mole% of P ₂ O _5; and at least about 12 mole% of Na ₂ O, and having A softening point of less than or equal to about 825 ° C and a high-temperature thermal expansion coefficient (high-temperature CTE) of less than or equal to about 30 ppm / ° C. In some embodiments, the softening point of the glass described herein is less than or equal to about 800 ° C, and in other embodiments, the softening point is less than or equal to about 775 ° C.

As discussed earlier, the high-temperature thermal expansion coefficient is considered the instantaneous thermal expansion coefficient of glass at high temperatures. FIG. 1 is a graph of the instantaneous thermal expansion coefficient of the sample 20 in Table 1 as a function of temperature. The high temperature CTE of this glass sample is the instantaneous CTE at a high temperature flat line occurring at about 675 ° C. In some embodiments, the high temperature thermal expansion coefficient is less than or equal to about 29 ppm / ° C, and in other embodiments, the high temperature thermal expansion coefficient is less than or equal to about 27 ppm / ° C. Exemplary compositions of these glasses are listed in Table 1. List in Table 2 the softening points, high-temperature thermal expansion coefficients, and other physical characteristics of the glasses listed in Table 1. These physical characteristics include strain point, annealing point, T ^200P , 10 ¹¹ poise temperature, T ^35kP , T ^{decomposition} , zircon Decomposition viscosity, T ^160kp , liquid temperature, liquid viscosity, refractive index and SOC.

In some embodiments, the glass described herein can be shaped into a three-dimensional shape using other means (including molding, etc.) known in the art. Non-limiting examples of such three-dimensional shapes include those whose at least one surface has a dish-like, curved, convex, or concave profile. The dish may have a generally flat portion surrounded by a curved portion on at least one side. The cross-sectional view in Figure 2 schematically illustrates a non-limiting example of a dish-shaped glass-ceramic article. The dish 200 has two major surfaces 202, 204, each major surface having a generally flat or planar portion 210 surrounded by a curved portion 220 on either end (or alternatively on both ends). Bundles to provide a dish-like outline or appearance. In other embodiments, the dish 230 has only one major surface 234 having a substantially flat or planar portion 210 that is bent on either end (or alternatively on both ends). Section 220 surrounds the bundle. The remaining major surface 232 is substantially flat or planar.

Ion exchange is widely used in chemically strengthened glass. In one particular example, basic cations in such a source of cations (e.g., molten salt or "ion exchange" baths) are exchanged with smaller basic cations in the glass to compressive stress near the glass surface (CS) ) Under the implementation layer. The compression layer extends from the surface to a depth of layer (DOL) within the glass. In the glasses described herein, for example, potassium ions in a cation source are ionized during ion exchange by immersing the glass in a molten salt bath containing a potassium salt such as, but not limited to, potassium nitrate (KNO ₃ ). Exchange with sodium ions in the glass. Other potassium salts that can be used in the ion exchange process include, but are not limited to, potassium chloride (KCl), potassium sulfate (K ₂ SO ₄ ), combinations thereof, and the like.

Figure 3 shows a schematic cross-sectional view of a flat ion exchange glass object. The glass object 300 has a thickness t , a first surface 310 and a second surface 312. Although the embodiment shown in FIG. 3 describes the glass article 300 as a flat, planar sheet or plate, the glass article may have other configurations, such as a three-dimensional shape or a non-planar configuration. The glass object 300 has a first compression layer 320 that extends from the first surface 310 to a layer depth d ₁ and reaches the body of the glass object 300. In the embodiment shown in FIG. 3, a glass article 300 also has a second compressed layer 322, the compression layer extending from the second surface 312 of the second layer to the depth d _2. The glass object also has a central region 330 extending from d ₁ to d ₂ . The central region 330 is under tensile stress or central tension (CT), which balances or cancels the compressive stress of the layers 320 and 322. The depths d ₁ and d _{2 of the} first compression layer 320 and the second compression layer 322 protect the glass object 300 from cracks introduced by sharp impacts from spreading to the first surface 310 and the second surface 312 of the glass object 300 while minimizing compressive stress The possibility that the crack penetrates the depths d ₁ and d ₂ of the first compression layer 320 and the second compression layer 322.

After being shaped into a three-dimensional shape, the glass objects described herein can be ion exchanged. In a non-limiting example, the glass is annealed at a temperature defined by 10 ^13.2 poise viscosity of the glass and ion exchanged in a molten potassium nitrate bath for up to 4 hours, 8 hours, or 10 hours. The ion exchange bath may contain almost 100% by weight of KNO ₃ . In some embodiments, the ion exchange bath may include at least about 95% by weight of KNO ₃ , and in other embodiments, at least about 92% by weight of KNO ₃ . The compression layer contains K ₂ O and has a maximum compressive stress of at least about 700 MPa. In some embodiments, one or more compressive layers (compressive layers 320, 322 in FIG. 3) may have a maximum compressive stress CS of at least about 700 MPa. In other embodiments, the maximum compressive stress is at least about 800 MPa, and in other embodiments, the maximum compressive stress is at least about 900 MPa. The layer depth DOL ( d ₁ , d ₂ in FIG. 3) of each of the compression layers 320, 322 is at least 20 μm in some embodiments. In other embodiments, the layer depth is at least about 30 μm.

Table 3 lists the compressive stress (CS), layer depth (DOL), and Vickers crack indentation thresholds obtained from the ion exchange of the glasses listed in Table 1. In the first set of ion exchange experiments, samples with a thickness of 1 mm were first annealed at a temperature defined by 10 ^13.2 poise viscosity of glass and then ion exchanged in a KNO ₃ bath at 410 ° C for up to 4 hours. In the second set of experiments, a 1-mm-thick sample was first heated to a temperature of 10 ¹¹ poise and quenched to room temperature in order to simulate the thermal history generated during the fusion drawing process. The quenched samples were then subjected to ion exchange in a KNO ₃ bath at 410 ° C. for up to 4 hours.

Table 3. Compressive stress (CS), layer depth (DOL) and Vickers crack indentation thresholds obtained from ion exchange of the glasses listed in Table 1.

In some embodiments, the glass described herein comprises: at least about 50 mole% SiO ₂ (ie, SiO ₂ ≧ 50 mole%); from about 10 mole% to about 20 mole% Al ₂ O ₃ (that is, 10 mol% ≦ Al ₂ O ₃ ≦ 20 mol%); from about 1 mol% to about 8 mol% P ₂ O ₅ (that is, 1 mol% ≦ P ₂ O ₅ ≦ 8 mole%); B ₂ O ₃ from about 2 mole% to about 10 mole% (ie, 2 mole% ≦ B ₂ O ₃ ≦ 10 mole%); and from about 14 Molar% to about 20 Molar% Na ₂ O (ie, 14 Molar% ≦ Na ₂ O ≦ 20 Molar%). The glass may further include ZnO from about 1 mole% to about 7 mole% (ie, 1 mole% ≦ ZnO ≦ 7 mole%).

In some embodiments, Al ₂ O ₃ (mol%)> P ₂ O ₅ (mol%) + B ₂ O ₃ (mol%) and Al ₂ O ₃ (mol%)> B ₂ O ₃ (Mole%), and in some embodiments, Na ₂ O (Mole%)> Al ₂ O ₃ (Mole%). In some embodiments, 0.3 ≦ [(R ₂ O (Mole%) + RO (Mole%) + B ₂ O ₃ (Mole%)] / [Al ₂ O ₃ (Mole%) + P ₂ O ₅ (mol%) + SiO ₂ (mol%)] ≦ 0.45, where R ₂ O is a monovalent cationic oxide and RO is a divalent cationic oxide. In some embodiments, the glass is substantially free of lithium , Potassium, alkaline earth metals, and at least one of the aforementioned compounds.

Each of the oxide components of the base glass and the ion exchange glass described herein serves a role. For example, silicon dioxide (SiO ₂ ) is the main glass forming oxide and forms the backbone of the network structure of the molten glass. Pure SiO ₂ has low CTE and is free of alkaline metals. However, due to the extremely high melting temperature, pure SiO _{2 is} incompatible with the fusion drawing process. The viscosity curve is also too high to match any core glass in the laminated structure. In some embodiments, the glass described in this document comprise at least about 50 mole% of SiO _2, included in other embodiments from about 50 mole% to about 65 mole% of SiO _2, and in other embodiments about 50 mole% to about 60 mole% SiO ₂ comprises from.

In addition to silicon dioxide, the glasses described herein include network structures Al ₂ O ₃ and B ₂ O ₃ to achieve stable glass formation, low CTE, low Young's modulus, low shear modulus, and Promote melting and forming. Similar to SiO ₂ , Al ₂ O _{3 is} used to provide rigidity to the glass mesh structure. Alumina can be present in the glass in four or five coordinations. In some embodiments, the glass described herein comprises from about 10 mole% to about 20 mole% of Al ₂ O _3, and in certain embodiments, comprises from about 12 mole% to about 16 mole% Al ₂ O ₃ .

Phosphorus pentoxide (P ₂ O ₅ ) is a network structure formed into these glasses. P ₂ O ₅ adopts a quasi-tetrahedral structure in a glass network structure; that is, P ₂ O _{5 is} coordinated with four oxygen atoms, but only three oxygen atoms are connected to the remainder in the network structure. The fourth oxygen is a terminal oxygen, which is double-bonded to the phosphorus cation. The association of boron and phosphorus in the glass network structure can lead to mutual stability of these network structure formations in a tetrahedral configuration, as is the case with SiO ₂ . Similar to B ₂ O ₃ , the incorporation of P ₂ O ₅ in the glass network structure is very effective in reducing Young's modulus and shear modulus. The incorporation of P ₂ O ₅ in the glass network structure also reduces the high temperature CTE, increases the rate of ion exchange interdiffusion, and improves the compatibility of glass with zircon refractories. In some embodiments, the glass described herein comprises from about 1 mole% to about 8 mole% of P ₂ O _5.

Boron oxide (B ₂ O ₃ ) is also a glass-forming oxide that is used to reduce viscosity and therefore improve the ability to melt and shape the glass. B ₂ O ₃ can be present in the glass network structure in triple or quadruple coordination. Triple coordination B ₂ O ₃ is the most effective oxide for reducing the Young's modulus and shear modulus, thereby improving the intrinsic damage resistance of glass. Thus, in some embodiments, the glass described herein contains from about 2 mole% to about 10 mole% of B ₂ O _3, and in other embodiments, comprises from about 5 to about 8 mole% Mo Ear% B ₂ O ₃ . The presence of both B ₂ O ₃ and P ₂ O ₅ in the glass enhances the mechanical performance of the glass by increasing the inherent damage resistance (IDR) of the glass. When ion exchanged, the glasses described herein exhibit a Vickers indentation threshold ranging from about 10 kgf to about 20 kgf.

The basic oxide Na ₂ O is used to achieve chemical strengthening of glass by ion exchange. The glass described herein include Na ₂ O, Na ₂ O salt bath may contain, for example, KNO ₃ and potassium exchange. In some embodiments, the glass comprises about 14 mole% to about 20 mole% from Na ₂ O, and in other embodiments, comprises from about 15 mole% to about 20 mole% of Na ₂ O. from

Similar to B ₂ O ₃ , the divalent oxide ZnO also improves the melting state of glass by reducing the temperature (200P temperature) at 200 poise viscosity. ZnO is also beneficial for improving strain points when compared to similar additions of P ₂ O ₅ , B ₂ O ₃ and / or Na ₂ O. In some embodiments, the glasses described herein include from about 1 mole% to about 7 mole% ZnO, and in other embodiments, from about 2 mole% to about 5 mole% ZnO.

Alkaline earth oxides including MgO and CaO can also be replaced by ZnO to achieve similar effects on 200P temperature and strain point. However, when compared to MgO and CaO, ZnO is less inclined to promote phase separation with the participation of P ₂ O ₅ . Other alkaline earth oxides, including SrO and BaO, can also be replaced by ZnO, but are less effective than ZnO, MgO, or CaO in reducing the melting temperature at 200 poise viscosity, and are also more effective than ZnO, MgO, or CaO in increasing the strain point Less effective.

In some embodiments, the base glass described herein can be formed by a pull-down process known in the art, such as a slot-drawing and a fusion-drawing process. The composition of the base glass containing the low concentration of Li ₂ O is completely compatible with the fusion drawing process and can be manufactured without problems. Lithium can be batched into spodumene or lithium carbonate.

The fusion drawing process is an industrial technology that has been used for large-scale manufacturing of thin glass sheets. Compared to other flat glass manufacturing technologies, such as float or slit drawing processes, the fusion drawing process produces thin glass sheets with excellent flatness and surface quality. Therefore, the fusion-drawing process has become the main manufacturing technology for manufacturing thin glass substrates for liquid crystal displays, as well as shields for personal electronic devices such as notebook computers, entertainment devices, tablet computers, laptop computers, and the like. glass.

The fusion drawing process involves flowing molten glass out of a groove called an "isopipe," which is usually made of zircon or another refractory material. The molten glass overflows from the top of the insulated pipe from both sides and converges at the bottom of the insulated pipe to form a single sheet, where only the inside of the final sheet is in direct contact with the insulated pipe. Since neither the exposed surface of the final glass sheet is in contact with the insulating tube material during the drawing process, the two outer surfaces of the glass are of original quality and do not require subsequent trimming.

In order to be fused and drawn, the glass must have a sufficiently high liquid viscosity (That is, the viscosity of the molten glass at the liquidus temperature). In some embodiments, the glasses described herein have a liquid viscosity of at least about 100 kilopoises. In other embodiments, the glasses have a liquid viscosity of at least about 120 kilopoises, and in other embodiments These glasses have a liquid phase viscosity of at least about 300 kilopoises.

Although typical embodiments have been described for the purpose of illustration, the foregoing description should not be construed as limiting the scope of the disclosure or the scope of the accompanying patent application. Therefore, without departing from the spirit and scope of this disclosure or the scope of the accompanying patent application, those skilled in the art can implement various modifications, adjustments and substitutions.

Claims (10)

A glass article comprising at least 50 mole% of SiO ₂ ; at least 8 mole% of Al ₂ O ₃ ; at least 1 mole% of P ₂ O ₅ ; at least 1 mole% of ZnO; and at least 12 Mole% Na ₂ O, wherein the glass object is ion-exchangeable and has a softening point of less than or equal to 825 ° C and a high-temperature thermal expansion coefficient of less than or equal to 30 ppm / ° C. The glass article according to the requested item 1, wherein the glass article comprises: from 50 mole% to 65 mole% of SiO _2; from 10 mole% to 20 mole% of Al ₂ O _3; from 1 mole % To 8 mol% of P ₂ O ₅ ; from 2 mol% to 10 mol% of B ₂ O ₃ ; and from 14 mol% to 20 mol% of Na ₂ O. The glass article according to claim 2, wherein the glass article further comprises ZnO from 1 mole% to 7 mole%. The glass article according to claim 2, wherein Al ₂ O ₃ (mol%)> P ₂ O ₅ (mol%) + B ₂ O ₃ (mol%), Al ₂ O ₃ (mol%) > B ₂ O ₃ (mol%) and Na ₂ O (mol%)> Al ₂ O ₃ (mol%). The glass article according to any one of claim 2, wherein 0.3 ≦ [(R ₂ O (mol%) + RO (mol%) + B ₂ O ₃ (mol%)] / [Al ₂ O ₃ (mol%) + P ₂ O ₅ (mol%) + SiO ₂ (mol%)] ≦ 0.45, where R ₂ O is a monovalent cationic oxide and RO is a divalent cationic oxide. The glass article according to claim 2, wherein the glass article does not contain at least one of lithium, potassium, and alkaline earth metals. The glass article according to claim 2, wherein the softening point is less than 800 ° C. The glass article according to any one of claims 1 to 7, wherein the glass article is an ion exchange type and has a compression layer having a layer depth of at least 20 μm extending from one surface of the glass article to the inside of the article, the The compression layer has a maximum compressive stress of at least about 700 MPa. The glass article according to claim 8, wherein the glass has a Vickers crack initiation threshold of at least 10 kgf. The glass article according to claim 8, wherein the glass article has a non-planar shape.